XL710 + QSFP-SFP-Adapter + E10GSFPSR

[indy]

Basically will the combination listed in the title work?

Bit of background:
A while ago I got my hands on 2x XL710 cards and an optical DAC cable for very little money.
Basically I have sweet 40G connection between my main PC and the FreeNAS server.

However now I want to move the server into a different room and the cable is too short.
Also I dont really want to drill massive holes for the QSFP connector to pass the cable to the next room.

One option would be 40G optical modules but with Intel locking other vendors out, the E40GQSFPSR module is a pricey option.
The multi-fiber cables are somewhat expensive as well and the MPO connector is almost a big as the module itself.

I would be willing to drop down to 10G however.
Intels 10G SR module is somewhat cheap, the cables are super-cheap and the LC connector is reasonably small.
However I would like to avoid having to buy 2x X710 cards as well.
And that is how we arrive at the combination mentioned in the title.
Unfortunately Intel does not offer QSFP-SFP adapters itself and I would like to avoid a bad buy or even damaging any equipment.

Any guidance is highly appreciated :)

 

[bigphil]

How long do the cables need to be? If you went down to 10Gb speed you could use DAC cables instead if the run isn't too long. Up to 7m for passive cables. I've got quite a few cables from 10gtek on Amazon and they work great for my X710's.

 

[indy]

Cable length with the most direct routing on the floor would have to be 10m at the very least... probably more like 15m though.

 

[indy]

Still looking for some guidance on the combination mentioned in the title.
Is it really that unusual?
I would imagine more admins paying the premium of 40G over 10G cards for future-proofing while using cheaper 10G links?

 

[indy]

Well I tried using an Intel-branded copper SFP-DAC and also an E10GSFPSR with a Mellanox QSFP-SFP adapter plugged into an XL710.
The cards don't seem to care for the Mellanox adapter but refuse operation as soon as either the DAC or transceiver is plugged into the adapter.
My conclusion is that Intel forbids any SFP module from being used in their QSFP cards.

 

[Jessep]

Try here for compatible transceivers:
https://www.fs.com/c/intel-40g-qsfp-1375

They will have cheap cables as well.

 

[indy]

Thanks for the tip, but in the meantime I 'downgraded' to SFP via a Mellanox ConnectX-3 card.
QSFP is just too cumbersome/expensive for home usage, I only bought those XL710 cards back then because Amazon had them priced incorrectly.